Conventional oscillator circuit configurations consist essentially of Colpitts, Hartley, Pierce, and Miller type configurations, or variations thereof. These configurations are generally unstable due to their inherent noise. The inherent noise, which is comprised of .sup.1 /f, shot, and thermal noise, causes random instantaneous changes in the quiescent current level of the oscillator. The random, instantaneous changes in quiescent current, in turn, produce instantaneous changes in the frequency generated. This effect is called phase noise, and it is generally defined as narrow band phase modulation by noise.
The usual approach to achieving oscillator stability is to utilize high-Q crystals in conjunction with active elements selected for their low noise characteristics. This approach, however, does nothing to reduce oscillator instability caused by inherent noise.